The circular stapler is a surgical instrument widely used in stitching and cutting operations on tubular tissue. The circular stapler comprises a circular stapling head assembly and an actuating assembly. After placing two sections of tubular tissue to be joined together between an anvil and a staple cartridge of the stapling head assembly, a distance between the anvil and the staple cartridge is then adjusted to tightly clamp two sections, and next, the actuating member is operated to fire the staples and join the two sections of tissue together.
In actual operation procedures, when performing two operations, i.e. lower rectal operation and gastric bypass operation, the circular stapler is difficult to enter tubular tissue. In the lower rectal operation, a circular stapler with the diameter of 33 mm, which must be performed via anus, is adopted. As the anus is a muscular opening and has small diameter in normal state, large-diameter instrument is very difficult to be inserted into the anus. In the gastric bypass operation, a circular stapler with the diameter of 25 mm, which must be performed in small intestine, is adopted. As the small intestine is an alimentary canal of the human body, there are a lot of mucous membranes in the inner wall thereof. However, the circular stapler has large end surface and the surface is not smooth enough due to the structural features. Therefore, the mucous membranes tend to be damaged when the circular stapler is moved through the small intestine.
To solve the above problems, a plurality of auxiliary instruments sleeved around the periphery of a staple cartridge assembly of a circular stapler was developed in the prior art, which are disclosed in U.S. patent publication Nos. US2009/0204108 and US2011/0114698. By means of the auxiliary instrument, the staple cartridge assembly of the circular stapler can be introduced into the human body and moved through intestinal tracts; and the auxiliary instrument can be disengaged from the staple cartridge assembly after the circular stapler arrives at a predetermined surgical position, without any influence on the subsequent procedures of the circular stapler. The current auxiliary instruments can help surgeons to smoothly place a head of the stapler into the predetermined position, but they must be torn and pulled out by large force. Thereby, tissues tend to be damaged accidentally, and hence, the use experience is poor. Moreover, as the auxiliary instruments are all sleeved around the periphery of the staple cartridge assembly, the outer diameter of the instrument is certain to be larger than that of the stapler, and thereby having an opposite effect of aggravating the pain of patients.